Partial or full cardiopulmonary bypass (hereafter "CPB") support is needed for medical procedures requiring general anesthesia where lung function is to be arrested during routine and high-risk cardiovascular, cardioneural and other surgical interventions including beating, fully arrested or partially arrested cardiac procedures, to maintain cardiovascular, cardioneural and corporeal support of the respective heart, cerebral and corporeal organ systems. Such surgical interventions include treatment of aneurysms, congenital valve disease, and coronary artery disease. Cardiac interventions such as angioplasty, atherectomy, thrombectomy, coronary bypass grafting, and heart valve repair or replacement are some of the other procedures that can be performed.
In procedures where the heart is to be fully or partially arrested, it has been conventionally preferred that the heart and coronary vasculature be isolated from the rest of the cardiovascular system by application of an external cross clamp or side biting clamp. Isolation allows antegrade or retrograde perfusion of cold, warm or normothermic oxygenated blood cardioplegia or crystalloid cardioplegia to the coronary arteries to aid in the preservation of the myocardium and to prevent dispersion of cardioplegia to the rest of the body. The heart chambers may then be vented for decompression and to create a bloodless surgical field for intracardiac interventions. For rapid cooling and arrest of the myocardium in open-chest procedures, direct application of a topical ice slush or cold pericardial lavage into the thoracic space is performed simultaneously while the cold coronary perfusion process is being accomplished. While the heart is arrested, oxygenated blood is perfused to the rest of the body to maintain cerebral and corporeal support without perfusion to the coronary arteries, which could resuscitate the partially or fully arrested heart and obscure the surgical field with blood before completion of the surgical intervention.
A preferred way to accomplish CPB is by inserting a venous cannula into a venous blood vessel, typically the vena cava, withdrawing deoxygenated blood and directing the fluid to a connected pump. The pump circulates the withdrawn blood through a blood oxygenator, heat exchanger and filter apparatus and then perfuses the oxygenated and temperature controlled blood and other fluids through an aortic perfusion catheter inserted into the aorta of the patient.
Stroke and neurological deficit are well documented sequelae of the above cardiac surgery procedure. Recent literature has documented that the incidence of stroke is as high as 6.1% with an additional 30-79% of patients suffering from some form of cognitive deficit. Neurological deficit varies from patient to patient, however common injuries include: loss of memory, concentration, hand-eye coordination, and an increase in morbidity and mortality. The impact on the patient is significant, but factors such as age, the level of intellectual activity and the amount of physical activity pursued by the patient prior to surgery all affect the quality of life. Finally, patients who suffer from neurologic injury have a substantially prolonged hospital stay, with an attendant increase in cost (Neurological Effects of Cardiopulmonary Bypass; Rogers AT, Cardiopulmonary Bypass Principles and Practice; Gravlee GP, 21:542).
One of the likely causes of stroke and neurological deficit is the release of emboli into the blood stream during heart surgery. Potential embolic materials include atherosclerotic plaques or calcific plaques from within the aorta or cardiac valves and thrombus or clots from within the chambers of the heart. These potential emboli may be dislodged during surgical manipulation of the heart and the ascending aorta or due to high velocity jetting (sometimes called the "sandblasting effect") from the aortic perfusion cannula. In addition, application and release of an external cross clamp or side biting clamp has been shown to release emboli into the blood circulation. Other potential sources of emboli include gaseous microemboli formed when using a bubble oxygenator for CPB and "surgical air" that enters the heart chambers or the blood stream during surgery through open incisions or through the aortic perfusion cannula.
The following Journal articles addressing specific problems associated with emboli are listed below:
Journal Articles relating to Cerebral Embolization and Adverse Cerebral Outcomes After Cardiac Surgery: Determination or Size of Aortic Emboli and Embolic Load During Coronary Artery Bypass Grafting; Barbut et al.; Ann Thorac Surg 1997; 63:1262-7; Aortic Atheromatosis and Risks of Cerebral Embolization; Barbut et al.; J Card & Vasc Anesth, Vol 10, No 1, 1996: pp 24-30. Aortic Atheroma is Related to Outcome but not Numbers of Emboli During Coronary Bypass; Barbut et al.; Ann Thorac Surg 1997, 64:454-9; Adverse Cerebral Outcomes After Coronary Artery Bypass Surgery; Roach et al.; New England J of Med, Vol 335, No 25, 1996: pp. 1857-1863; Signs of Brain Cell Injury During Open Heart Operations: Past and Present; .ANG.berg; Ann Thorac Surg 1995, 59:1312-5; The Role of CPB Management in Neuro behavioral Outcomes After Cardiac Surgery; Murkin; Ann Thorac Surg 1995,59:1308-11; Risk Factors for Cerebral Injury and Cardiac Surgery; Mills; Ann Thorac Surg 1995, 59:1296-9; Brain Microemboli Associated with Cardiopulmonary Bypass: A Histologic and Magnetic Resonance Imaging Study; Moody et al.; Ann Thorac Surg 1995, 59:1304-7; CNS Dysfunction After Cardiac Surgery: Defining the Problem; Murkin; Ann Thorac Surg 1995,59:1287; Statement of Consensus on Assessment of Neurobehavioral Outcomes After Cardiac Surgery; Murkin et al.; Ann Thorac Surg 1995, 59:1289-95; Heart-Brain Interactions: Neurocardiology Comes of Age; Sherman et al.; Mayo Clin Proc 62:1158-1160,1987; Cerebral Hemodynamics After Low-Flow Versus No-Flow Procedures; van der Linden; Ann Thorac Surg 1995, 59:1321-5; Predictors of Cognitive Decline After Cardiac Operation; Newman et al.; Ann Thorac Surg 1995,59:1326-30. Cardiopulmonary Bypass: Perioperative Cerebral Blood Flow and Postoperative Cognitive Deficit; Venn et al.; Ann Thorac Surg 1995, 59:1331-5; Long-Term Neurologic Outcome After Cardiac Operation; Sotaniemi; Ann Thorac Surg 1995, 59:1336-9; Macroemboli and Microemboli During Cardiopulmonary Bypass; Blauth; Ann Thorac Surg 1995, 59:1300-3.
Recently, there has been much development in the area of minimally invasive cardiac surgery (MICS) and the use of balloon catheters to address the clinical problems associated with a conventional median stemotomy and the attendant use of a cross clamp to occlude the ascending aorta. For example, U.S. Pat. No. Re 35,352 to Peters describes a single balloon catheter for occluding a patient's ascending aorta and a method for inducing cardioplegic arrest. A perfusion lumen or a contralateral arterial cannula is provided for supplying oxygenated blood during cardiopulmonary bypass. U.S. Pat. No. 5,584,803 to Stevens et al. describes a single balloon catheter for inducing cardioplegic arrest and a system for providing cardiopulmonary support during closed chest cardiac surgery. A coaxial arterial cannula is provided for supplying oxygenated blood during cardiopulmonary bypass. The occlusion balloon of these catheters must be very carefully placed in the ascending aorta between the coronary arteries and the brachiocephalic artery, therefore the position of the catheter must be continuously monitored to avoid complications.
In clinical use, these single balloon catheters have shown a tendency to migrate in the direction of the pressure gradient within the aorta. More specifically, during infusion of cardioplegia, the balloon catheter will tend to migrate downstream due to the higher pressure on the upstream side of the balloon and, when the CPB pump is on, the balloon catheter with tend to migrate upstream into the aortic root due to the higher pressure on the downstream side of the balloon. This migration can be problematic if the balloon migrates far enough to occlude the brachiocephalic artery on the downstream side or the coronary arteries on the upstream side.
Another important development in the area of aortic balloon catheters is the concept of selective aortic perfusion. Described in commonly owed U.S. Pat. Nos. 5,308,320, 5,383,854 and 5,820,593 by Peter Safar, S. William Stezoski, and Miroslav Klain is a double balloon catheter for segmenting a patient's aorta for selective perfusion of different organ systems within the body. Other U.S. patents which address the concept of selective aortic perfusion include; U.S. Pat. No. 5,738,649, by John A. Macoviak, U.S. Pat. Nos. 5,827,237 and 5,833,671 by John A.
Macoviak and Michael Ross; and commonly owned, copending patent application Ser. No. 08/665,635, filed Jun. 18, 1996, by John A. Macoviak and Michael Ross. All the above listed patents and patent applications, as well as all other patents referred to herein, are hereby incorporated by reference in their entirety.
Safar teaches the peripheral introduction of an aortic balloon catheter to establish CPB and to facilitate intravascular surgical interventions. Additionally, Safar teaches an apparatus and method of selective differential perfusion, which allows segmentation of the circulatory system into separate coronary, cerebral and corporeal subcirculations. The aortic balloon catheter allows establishment of CPB without the need for a thoracotomy, which may also facilitate minimally-invasive surgical procedures on the arrested heart. Although minimally invasive techniques provide a beneficial alternative to the open chest median stemotomy, the present invention specifically addresses a method where a thoracotomy, such as a median stemotomy, is desirable because of the need for direct exposure of the heart and an apparatus specifically designed for such a purpose.
U.S. Pat. No. 5,697,905 to d'Ambrosio teaches a single balloon, triple lumen catheter to be positioned in the ascending aorta to reduce the release of embolized air and particulate matter into general body circulation. The aforementioned device uses a suction lumen to remove released emboli.
The following U.S. patents relate to aortic filters associated with atherectomy devices in order to trap potential emboli before they are introduced into the general circulation: U.S. Pat. Nos. 5,662,671 and 5,769,816. The following international patent applications also relate to aortic filters and aortic filters associated with atherectomy devices: WO 97/17100, WO 97/42879, WO 98/02084.
Catheters intended to occlude the descending aorta are disclosed by Manning, U.S. Pat. Nos. 5,678,570, 5,216,032, and Paradis, U.S. Pat. No. 5,334,142. However, none of the aforementioned devices were designed, nor intended, for use in the manner of the present invention.
The previous inventions do not adequately address the patient population where a conventional median stemotomy and differential perfusion are desirable. Therefore, what has been needed and previously unavailable is an apparatus and system to selectively and differentially perfuse the cerebral sub-circulation with hypothermic oxygenated blood and perfuse the corporeal sub-circulation with normothermic oxygenated blood. The present invention solves this immediate problem, as well as others.